The IOS version of my ipad3 is 8.4.1,and most VPN apps don’t work on the ipad3. How to use VPN?
The most sound advice you’ll receive here is to upgrade to a more modern iPad, since the iPad 3 is now horribly out of date and has been obsolete for years.
Can you configure directly in settings? I can’t remember which version of iOS that was added in.
Otherwise your best option is to connect to a hotspot or router you can run the con on.
Maybe you have a Router (ASUS with Merlin firmware preferably), which you can install VPN on. Then tell your router if your iPad makes a connection to it, it should use the VPN always. And you are done.
I don’t think you’ll find any supported applications in the app store, but you can manually set up an l2tp, ipsec, ikev2 vpn in settings. Expressvpn for exaple allows you to do that.